Paper punches are well know in the art and are found in nearly every office which generates or handles documents.
Paper punches are commonly available in single hole varieties, in two and three hole varieties, and in multi-hole varieties which allow the user to adjust the distance between the various holes punched.
Almost all of these punches use the same basic punching tool; namely, one or more of a punch rod sharpened at the lower end, and a cooperating punch die which is coaxially aligned with the punch rod, and which receives the punch rod as it is pushed through the sheet being punched.
In addition, there is some means of applying a downward pressure to the punch rod, usually involving some kind of lever system to create mechanical advantage.
FIG. 1 shows a typical prior art punch. The punch rod 101 is retained by a coil spring 301. The punch die 140 resides in a lower assembly 120 and is coaxially aligned with the guide 280 which constrains the vertical movement of the punch rod. A handle 160 provides mechanical advantage to push down on the top of the punch rod.
The paper sheet to be punched is disposed in the space between the upper and lower parts of the punch. However, the paper cannot be inserted past the throat 144 of the punch. As a result, the maximum distance between the edge of the paper and the punch rod-die axis is constrained to a relatively small displacement, as may be seen by referring to this Figure.
Virtually all of the simple punches based on the principles stated above have the same shortcoming, that is, the inability to allow a user to punch holes near the center of a sheet. This shortcoming is a result of the necessity in prior art punches to provide a physical connection between the upper assembly of the punch, containing the punch rod, and the lower assembly, containing the punch die. As the distance between the punch rod-die axis to the throat becomes greater, the punch device becomes extended in size and must become increasingly bulkier and reinforced in order to support what is essentially a pair of cantilevered members having a moment arm equal to the distance from the throat to the punch rod-die axis.
The present invention provides a simple, compact punch which overcomes the inherent structural problems of prior art punches by omitting the physical connection between the upper and lower assemblies of the prior art punch, and instead provides alignment of the punch rod and punch die by means of magnetic alignment of these to elements.